Objective performance goals of safety and blood pressure efficacy for clinical trials of renal artery bare metal stents in hypertensive patients with atherosclerotic renal artery stenosis

Objective : To provide safety and performance goals for prospective single‐arm trials of bare metal renal artery stenting in patients with resistant hypertension associated with high grade atherosclerotic renal artery stenosis. Background : To date, there have been no US Pre‐Market Approval (PMA) bare metal renal stent device trials which have focused on improvement of blood pressure control as a primary effectiveness endpoint. Methods : Analysis of subject‐level data from three large industry sponsored pre‐market approval (PMA) trials was performed. Hypertensive patients (≥155 mmHg) with a ≥50% atherosclerotic renal artery stenosis were included. Thirty day and 9‐month systolic and diastolic blood pressure measurements, renal function and 9‐month duplex ultrasound assessment of renal artery patency were analyzed. Results : Initial data analysis of 600 patients from the 3 PMA trials identified 286 patients who met inclusion criteria. The mean baseline systolic blood pressure was 177.8 ± 19.3 mmHg with a mean 68.1% diameter renal artery stenosis. Nine months after successful stenting, the mean SBP was 156.7 ± 24.1 mmHg; the 9 month restenosis rate was 14.4%. Conclusion : Based on the statistical modeling of these data and a priori established performance criteria, the co‐primary endpoints of 9 month reduction in blood pressure and in‐stent restenosis are proposed. The reduction in blood pressure will be analyzed as a continuous variable and will be compared to this performance goal. © 2011 Wiley‐Liss, Inc.     

Pulmonary instillation of multi-walled carbon nanotubes promotes coronary vasoconstriction and exacerbates injury in isolated hearts

The growing use of multi-walled carbon nanotubes (MWCNTs) across industry has increased human exposures. We tested the hypothesis that pulmonary instillation of MWCNTs would exacerbate cardiac ischaemia/reperfusion (I/R) injury. One day following intratracheal instillation of 1, 10 or 100 μg MWCNT in Sprague-Dawley rats, we used a Langendorff isolated heart model to examine cardiac I/R injury. In the 100 μg MWCNT group we report increased premature ventricular contractions at baseline and increased myocardial infarction. This was associated with increased endothelin-1 (ET-1) release and depression of coronary flow during early reperfusion. We also tested if isolated coronary vascular responses were affected by MWCNT instillation and found trends for enhanced coronary tone, which were dependent on ET-1, cyclooxygenase, thromboxane and Rho-kinase. We concluded that instillation of MWCNTs promoted cardiac injury and depressed coronary flow by invoking vasoconstrictive mechanisms involving ET-1, cyclooxygenase, thromboxane and Rho-kinase.